With increasing development of science and technology, computers and their peripheral devices are widely and deeply applied to all families and all industries. During the process of fabricating a computer and the peripheral devices, it is important to quickly test the circuits of the circuit board of the computer and the peripheral devices in order to assure the normal operations of the computer and the peripheral devices.
Conventionally, the circuit board is placed in an in circuit tester (ICT) or a functional circuit tester (FCT), and the electrical properties of the circuit board are tested by the in circuit tester or the functional circuit tester. The bed of nails in a test platform of the in circuit tester or the functional circuit tester is electrically contacted with pre-defined test points of the circuit board in order to test whether the electronic components or the circuits of the circuit board are normal. Consequently, during the process of assembling the circuit board, the problems associated with non-wet open, the solder short, misalignment, missing parts or wrong parts will be reduced.
For increasing the testing accuracy of the in circuit tester or the functional circuit tester, the stress provided to the bed of nails or the pressing element is usually provided by an external instrument. Consequently, the external instrument judges whether the pressed circuit board is in a horizontal state.
However, since the external instrument is only able to judge whether the circuit board is in flat placement, some drawbacks occur. For example, if the bed of nails in a test platform of the in circuit tester or the functional circuit tester malfunctions or the bed of nails is not accurately in electrical contact with the circuit board, the test worker cannot realize the abnormal condition of the bed of nails. Under this circumstance, an erroneous test result is generated. Consequently, during the process of testing the circuit of the circuit board, it is important to place the circuit board on the same horizontal plane while monitoring the contact element. For example, it is necessary to monitor the function of the bed of nails and assure that the contact element is accurately in electrical contact with the circuit board.